I am looking for a better logical solution of a situation where one core Java EE (Web) application will call/execute many other Java applications/workers (which can be core Java or J2EE(web) application (don't know what will be the best)) at a certain time.
Those other Java applications/workers will basically connect (individually) with different Data sources (can be from remote DB or REST or SOAP, etc...) and populate/update local DB at a certain period of time.
I was doing research on Java Quartz Scheduler recently. Do u have any good suggestion to me for this Enterprise level architecture?
Btw, I am using Spring 4, Java 7
Thank you as always for all good and professional ideas.
Sample diagram can be as follows:
You can connect your java application with others easy with spring's httpInvoker or rmiInvoker.
More information here: http://docs.spring.io/spring/docs/current/spring-framework-reference/html/remoting.html
Not sure to understand good, but you can look at a messaging mechanism. Typically, the WebApp will send a message that will be received by all the Workers.
Have a look a JMS which it designed for this kind of use, and integrates well with both JEE (it is a part of the JEE spec) and Spring.
There are basically two parts to your question:
How do I schedule jobs on a Java EE server?
How do I invoke remote services from that scheduled job?
Job Scheduling
The trick with job scheduling in a Java EE environment is that you are typically running jobs in a cluster, or more than one server. Thus, only one of the nodes should be running that job at a time "on behalf of" the cluster, otherwise, you'll get multiple calls to those remote resources for the same thing.
There is a standard out there for this, JSR-237, which covers Timers and WorkManagers. Each Java EE vendor has its own implementation. WebLogic has one, WebSphere has one, and JBoss has one (the JBoss one isn't compliant with the JSR, but it does the same thing).
If you are running one of the servers that only runs the web tier of the Java EE spec (i.e, Tomcat or Geronimo), then Quartz is a good choice.
How to invoke remote services from timed jobs
Echoing #Alexandre Cartapanis' answer, probably what you'll want to do is create a JMS Topic in your Java EE server, and then when the job runs, post a message to the topic. The remote services (whatever Java EE servers) subscribe to this topic, and then you can run your queries.
The big advantage here is that if you ever need to add another service that needs to populate the local DB, all you have to do is have that server subscribe to the topic - no code changes needed. With JSch or remoting, you'll have to make a code change every time a new service comes online. You also have to make code changes if DNS addresses or IP addresses change, etc, where as the JMS way is just configuration on the server. There's a lot more that you can do with JMS, and the support is much better across the board.
Spring has adapters for Quartz and I think there's one out there for WorkManagers and Timers too.
You can make use of JSch - Java Secure Channel to trigger remote ssh calls which can start a JVM and run the Worker class.
Here are some examples.
Related
I am new to clustering on Weblogic and read this tutorial. Now I want to know that is that possible to cluster any java application on Weblogic? in that tutorial is discussed about Ejb-based applications. My application has no framework and is just simple JavaEE application and I want to cluster it on weblogic.
Yes, you can.
This is simply replicate your app into multiple servers and a load balancer on top of these will distribute the requests among them.
You have to only check your resource (server, database etc.) support it and there is no multithreading / concurrency issue with your code.
For my Spring-based web application, I now have the requirement to send out weekly e-mails to my application's users.
What are elegant solutions to this requirements?
Up until now, I have come up with the following possible solutions:
a dedicated cron job that I schedule to run once a week, running independently from my web application JVM process and outside of the web application Servlet container. This process takes care of sending out those weekly e-mails. To accomplish sending personalized e-mails, it reuses domain classes (such as my User class) that I have already developed for my web application. This dedicated process accesses my application's MySQL database concurrently to the running Spring Web MVC servlet?
a scheduled mechanism inside my Spring Web MVC servlet or inside my Servlet container.
In this setup, the e-mail sending happens inside the same JVM and the same servlet container as my web-serving Spring Web MVC servlet. Maybe this setup has (irrelevant?) advantages such as "database connection pool sharing" and "transaction sharing" "class sharing" with the servlet hosted inside the same environment.
Using or not using Spring Batch, for any of the above conceived setups. I have no experience right now with Spring Batch as to judge whether Spring Batch is or isn't an adequate tool for my requirement.
Maybe there are other solutions as well?
I am especially interested in answers that can give insights and guide in making an educated decision.
It is irrelevant for this particular question whether e-mails get sent with my own infrastructure or with a third party e-mail SaaS service.
From your description, the code for generating newsleters must share common code base with your main application. So the natural solution is to develop this code withing your main application. The open case is how this code is triggered:
From CRON. You start a script from CRON that would trigger the function within you application somehow. This somehow may be a process listening on specific port, or, what is quite natural for web application, a dedicated URL that would trigger newsletter. Just make sure that URL can't be run from outside, only from localhost (check caller IP, for example). You must, however, deal with the situation, that your app is down (restarting for example) when CRON launches the script.
From within the application. For example, using Quartz. The minus is that you need to include new library, create database tables for Quartz. The plus - Quartz will handle situation, when the task was scheduled on the moment when the application was down, because it stores the information about what was launched in DB.
We always use cron to fire a JMS message to a queue and have a dedicated process which consumes these messages. You can add the email contents to the message or just use the message as a trigger. The nice thing about this approach is you can fire in a JMS message from anywhere and have multiple handlers lots of different email scenarios. The only downside is installing a JMS broker, if you don't already have one...
I am building a Spring-MVC based web application which is required to send a weekly newsletter to a small group of people. I am using Spring's built-in scheduling mechanism. http://static.springsource.org/spring/docs/3.0.x/reference/scheduling.html‎
Yes, in this setup, the e-mail sending happens inside the same JVM and the same servlet container and it is quite easy and handy to implement the solution. I am observing the stability and reliability of this mechanism and cannot feedback more about it now.
I am currently developping an application which will be deployed in a weblogic application server cluster. This application is consuming some JMS messages through a MDB and process some business logic through AKKA actors.
Some of these agents are singleton and others are grouped in a pool and contact through a round-robin router.
I am trying to figure out how all these things will work in a clustered environment:
Is it possible to create a "unique" AKKA system even if the application is deployed on several nodes in the cluster? Do agents created on each server will known each other?
It it possible to add new weblogic node in the cluster and have AKKA framework recognize these new resources?
How configure all these things?
For what i see in AKKA documentation about the cluster implementation, it seems that the architecture supported is outside an application server, with AKKA nodes started from a java shell command.
Sadly, i have not found any valuable information on the use of AKKA in a application server environment.
Thanks for your help
When you say Akka agents, you mean actors? Also, I assume that round-robin dispatcher is a RoundRobinRouter :)
Akka does not have explicit support for application servers, but you should be able to instantiate an ActorSystem in your code.
As for "uniqueness", if you use clustering, the membership is maintained automatically for you so you can see which nodes are available, and you can add nodes easily. There is currently no naming service implemented on top of that, that is the target of a later version, so you have to take care of finding an actor inside the cluster yourself, or handling singletons global to the cluster.
I recommend reading the relevant sections in the documentation how you can set up and configure your cluster.
http://doc.akka.io/docs/akka/2.1.0/cluster/index.html
I am writing a web application to be deployed on tomcat. I am writing a servlet. When I receive a request, I need to call 10 other different websites. Then aggregate responses received from all of them and respond. Now if i call every website in a sequence, it takes lot of time. Is there a way to complete this task in parallel?
I mean is there a way to call 10 websites in parallel? Can I use java multi-threading?
Consider to use a Java EE 6 compliant application server such as GlassFish.
EJB 3.1 introduced asynchronous method calls:
http://java.sun.com/developer/technicalArticles/JavaEE/JavaEE6Overview_Part3.html#asynejb
http://download.oracle.com/javaee/6/tutorial/doc/gkkqg.html
You could use threading, but it would probably be alot easier if you used e.g., HttpClient with a connection pool of 10.
See 2.8.4 Pooling connection manager for further configuration details.
In a very popular ecommerce store, I'd imagine the actual processing of the credit card would be moved to some sort of dedicated application server, and made into more of a asynchronous process.
What sort of java application type would that be? i.e. a service that would take a message of the queue, and start processing the request and update some db table once finished.
In .net, I guess one would use a windows service. What would you use in the java world?
It is typically a J2EE application that uses a HTTP web service interface or a JMS messaging interface. HTTP interfaces are accessible via a URL, and JMS connects to a queue to pick up messages that are sent to it. The app can run on any one of the major commercial (WebSphere, Weblogic, Oracle) or free (Glassfish, JBoss) servers.
In Java you already have great open source projects that do all this for you like Glassfish, Tomcat etc.
For a mission critical system, you might want something like IBM MQ series as the middleware, and a straight Java application that uses the MQ interface to process the requests.
At a few banks that I know of, this is their architecture. Originally the application servers were written in C, as was the middleware. They were able to switch to java because the code that was actually doing the critical work (sending and receiving messages, assuring guaranteed delivery, protecting against interruptions if a component went down) were the IBM MQ's.
In our case we use an application server from Sybase that can house Java components. They are pretty much standard Java classes that have public methods that are exposed for calling via CORBA. Components can also be scheduled to run constantly or on a schedule (like a service) to look for work to do (via items in a database table, an Oracle AQ queue, or a JMS queue). All of this is contained in the app server and the app server provides transaction management, resource management, and database connection pooling for us.
Or use an OSGI environment.